SFF's oil storage installation at Saldanha is the largest facility of its kind in the world. It comprises six in-ground concrete storage tanks which have a combined capacity of 45 million barrels of oil. The tanks are linked by pipeline to an oil terminal at the Port of Saldanha where tankers either discharge or backload oil. A second 107 km long pipeline links the oil storage facilities with the Caltex refinery at Milnerton and conveys most of the refinery's crude oil requirements. Although Caltex imports crude oil independently of SFF's operations, the refinery is currently dependent on access to the Saldanha oil terminal and to SFF's oil storage infrastructure for most of its oil supply (currently about 80 percent, in future, probably 100 percent of the refinery's oil supply).
Strategic oil storage in South Africa
During the period of economic sanctions against South Africa, SFF's primary role was to procure, store and supply crude oil to the domestic refining industry. Although the lifting of sanctions has reduced the role of SFF as a supplier of crude oil, an essential part of the organisation's current business still relates to the maintenance of South Africa's strategic physical reserves of crude oil. The target volume of oil that will be held in stock by SFF will match the refining needs for approximately 90 days of petrol consumption in South Africa; in 1997 this will amount to about 39 million barrels and will increase to a projected volume of 59 million barrels by the year 2002. SFF plans to hold a maximum of 10 million barrels of oil at the Ogies mine storage facility in Mpumalanga Province and to utilise the Saldanha storage tanks to hold the bulk of the reserve.
Rationale behind the SFF project proposal
The oil storage capacity and strategic reserves held in South Africa currently exceed the country's minimum requirements. In order to reduce the surplus, SFF is supplying oil from Ogies to domestic refiners and is involved in trading activities with local and international buyers using the Saldanha facilities; currently policy permits SFF to trade an oil turnover equivalent to 15% of the strategic reserve. Trading profits are adequate to meet SFF's operating costs but do not offset the interest payable on the value of oil held in storage for strategic purposes. SFF proposes that the economic impact of this cost on the national fiscus could be reduced through a joint venture oil storage and trading agreement with an oil-producing country, such as Iran.
Port Design Considerations
The design vessel for Saldanha is specified as a 250 000 dwt(1) tanker with a maximum length of 340 metres and a draught of 20.5 metres.
The diameter of the turning basin within the port entrance channel has been dredged to achieve a ratio of basin diameter over ship length of 2. Tankers which are chartered by SFF are typically in the 250 000 to 300 000 dwt class and, in the case of the larger vessels, the ratio of basin diameter over ship length is decreased to about 1.7. The continued utilization of the port by such vessels will require dredging to increase the diameter of the turning basin; similarly, the width of the port entrance channel will need to be increased to safely accommodate the width of the largest tankers serviced at the oil terminal. Dredging will not be required if the dimensions of tankers chartered by SFF (and Caltex) remain within the port design specifications.
The oil berth is not well protected from wave action due to its alignment with the approach direction of the predominant south-westerly swells. Mooring is also aggravated by waves which refract into the port (Small Bay) and, after reflecting against the shoreline, cause vessel instability. Under unfavourable sea state conditions vessels cannot be moored securely and occasionally are required to leave port.
1 Dwt (dead weight tonnage) is the total carrying capacity of a ship for cargo, fuel, water and other equipment and supplies and is measured in long tonnes of 1016 kg.
Physical environment
- Coastal features: The West Coast is characterised by an open coastline which is exposed to a generally high energy wave regime. Two prominent coastal features are the Saldanha Bay - Langebaan Lagoon system and St Helena Bay, in which more sheltered conditions prevail. Saldanha is the largest enclosed bay on the west coast of Southern Africa.
- Geology and hydrogeology: The surface sedimentary geology of the low-lying areas around Saldanha consists mainly of calcretised and unconsolidated coastal and marine deposits; these are underlain by granite bedrock. Although the sedimentary formations in the area constitute an important primary aquifer, the groundwater beneath the SFF oil storage facility is saline and is not potable.
- Wind: The local wind regime is significant in the context of the EIA since circulation within Saldanha Bay is influenced to a large extent by the wind; in the event of oil spills, this exposes certain shoreline areas to the risk of oiling. Upwelling of nutrient-rich water offshore of Saldanha is the reason for the high biological productivity within the marine ecosystem; upwelling is caused by strong winds which blow predominantly from the southerly sector.
- Currents and circulation: Circulation and currents within the Saldanha - Langebaan system are influenced by the local geometry, the combination of wind and tides and the variation in temperature between the surface and bottom water. The predominant south-southeasterly wind causes a weak clockwise circulation in Small Bay and a stronger anticlockwise circulation in Big Bay. Under north-westerly wind conditions, the circulation in Big Bay is clockwise.
- Waves: The most frequently occurring swells originate from the south-southwesterly to west-southwesterly sector. Due to the south-westerly facing channelled entrance to Saldanha Bay the system is, therefore, relatively open to penetration by the predominant deep-sea swells. The shoreline of Big Bay located directly opposite the entrance to Saldanha Bay experiences the highest wave energies.
- Nearshore coastal processes and shoreline dynamics: The main processes which control the dynamics of the soft shoreline of Saldanha Bay are waves and currents which have the capacity to mobilise and transport beach sediments. The average long-term rate of littoral transport along the northern shoreline of Big Bay is about 150 000 m3/year in the direction of the iron ore and oil jetty; along the southern shoreline of the bay the net direction of littoral transport, which is about 50 000 m3/year, is towards Langebaan.
- Marine water quality: The greatest potential impact of SFF's operations on marine water quality is contamination by hydrocarbons and trace metals associated with the transportation of crude oils and the disposal of ballast water. The present water quality status indicates that hydrocarbon concentrations in the bay sediments and mussel tissue are quite low (these components of the marine environment can accumulate chemical compounds and can reflect changes in water quality over time). Trace metal concentrations in sediments are high in the vicinity of the oil jetty and iron ore handling quay; however, these levels do not constitute serious contamination and are low compared with other harbours in South Africa. (Note: the contamination is not attributable only to SFF's operations but also to other port- and non port-related activities).
